10 Dec
2005
10 Dec
'05
6:11 a.m.
Noooooo........! DAA has a very useful function.
AND AL,00fh
ADD AL,090h
DAA
ADC AL,040h
DAA
RET
Now, what's it do?
--jc
Chuck Guzis wrote:
On 12/9/2005 at 9:16 PM Jim Battle wrote:
On pages 97-98 he is discussing flags and DAA. He
mentions that the only
flag that really needs to be changed on a DAA is the carry flag, but to
increase compatibility with 8080 code, they set all five flags like the
8080.
Which brings us back to the original subject, doesn't it? Current fancy
x86 still harks from the 8008 in that the old DAA is STILL there, although
heaven knows who still uses it (or why. I know the 4004 also had a DAA,
but I don't count it as the 8008 doesn't really descend from the 4004).
Maybe it's time to say goodbye to DAA and the rest of the cruft.
Cheers,
Chuck